On the vectorial nature of the rotational degrees of freedom in spatial beam elements

In this note, it is shown that the rotational degrees of freedom at a node of a spatial finite beam element are the components of a vector regardless of their magnitudes, as long as the structure to be analysed is composed of slender beams, and what may prevent them from being considered as the components of a vector is the presence of significant transverse shear strains, which usually appear in short beams, rather than the magnitudes of the rotations.